Efficiency of Single Phage Suspensions and Phage Cocktail in the Inactivation of Escherichia coli and Salmonella Typhimurium: An In Vitro Preliminary Study

Abstract

Enterobacteriaceae Escherichia coli and Salmonella enterica serovar Typhimurium strains are among the main pathogens responsible for moderate and serious infections at hospital and community environments, in part because they frequently present resistance to antibiotics. As the treatment of Enterobacteriaceae infections is empiric, using the same antibiotics to treat E. coli and Salmonella infections, the same concept can be applied with phages. The use of different phages combined in cocktails, frequently used to circumvent the development of phage-resistant mutants, also allows for the treatment of multiple pathogens, broadening the phages’ action spectrum. As such, the aim of this study was to evaluate the efficiency of a cocktail of two phages (ELY-1, produced on E. coli and phSE-5, produced on S. Typhimurium) to control E. coli and S. Typhimurium. Phages ELY-1 and phSE-5 were effective against E. coli (maximum reductions of 4.5 and 3.8 log CFU/mL, respectively), S. Typhimurium (maximum reductions of 2.2 and 2.6 log CFU/mL, respectively), and the mixture of both bacteria (maximum reductions of 2.2 and 2.0 log CFU/mL, respectively). The cocktail ELY-1/phSE-5 was more effective against S. Typhimurium and the mixture of both bacteria (maximum reduction of 3.2 log CFU/mL for both) than the single phage suspensions and as effective against E. coli as its specific phage ELY-1 (maximum reductions of 4.5 log CFU/mL). The use of both the phage cocktails, as well as the single-phage suspensions, however, did not prevent the occurrence of phage-resistant mutants. Overall, the results indicate that the application of the phages in the form of a cocktail show their potential to be used presumptively, that is, prior to the identification of the pathogens, paving its use to control E. coli or S. Typhimurium.

Effect of a bacteriophage T5virus on growth of Shiga toxigenic Escherichia coli and Salmonella strains in individual and mixed cultures

“…In addition, this finding was consistent with earlier reports that phage av-08 (unknown taxonomy) was able to decontaminate S. Montevideo and STEC O157:H7 on chicken skin [14]. Costa et al [15] also found that single phage ELY-1 or phSE-5 (unknown taxonomy) reduced number of non-O157 E. coli and S. Typhimurium ATCC13311 in a mixture, although this reduction was less than produced by a cocktail of both of these phages in broth culture. The relative contribution of polyvalent phages vs phage cocktails to bacterial biocontrol remains unclear.…”

Combined Application of Bacteriophages and Carvacrol in the Control of Pseudomonas syringae pv. actinidiae Planktonic and Biofilm Forms

“…The emergence of phage-resistant bacterial mutants is a major concern in phage therapy [9,13,38], and this drawback has been overcome through different strategies. Mateus et al [11], Costa et al [14] and Hooton et al [39] found that the emergence of phage-resistance in different bacteria can be prevented by using bacteriophage cocktails. Lopes et al [13] reported that combined treatment with phages and antibiotics is effective in preventing the emergence of phage-resistance in Escherichia coli.…”

“…Other studies also described new phages active against Psa [7,8], but only a few studies have evaluated the therapeutic potential of phages in controlling this phytopathogen [9,10]. No studies with phage cocktails, or with combined therapies including phages, have yet been evaluated against Psa; approaches that, besides increasing the effectiveness of the treatment, prevent the development of bacterial resistance to phages [11][12][13][14].…”

Application of a Broad Range Lytic Phage LPST94 for Biological Control of Salmonella in Foods

“…Efficiency of plating (EOP) was determined as described previously [35,38]. Test bacterial strains were grown overnight at 37 • C and 100 µL of each of the test bacterial cultures was used in double layer assays together with 100 µL of 10 6 -10 9 -fold diluted phage lysate.…”